/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to you under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.calcite.util.format;

import java.util.List;
import java.util.Map;

/**
 * Describes the format strings used by a formatting function such as
 * {@code FORMAT_TIMESTAMP} or {@code CAST(string AS DATE FORMAT formatString)}.
 *
 * <p>Can parse a format string to a list of format elements.
 *
 * @see FormatModels
 */
public interface FormatModel {
  /** Returns the map used to create the {@link FormatModel} instance. */
  Map<String, FormatElement> getElementMap();

  /** Parses a format string using element identifiers supplied by
   * {@code format}. */
  List<FormatElement> parse(String format);

  /** As {@link #parse}, but does not cache. */
  List<FormatElement> parseNoCache(String format);
}
